1. Field of the Invention
This invention relates to optical waveguides and more particularly to birefringent optical channel waveguides which selectively guide a particular mode of polarized light.
2. Background of the Prior Art
Polarizing optical waveguides, i.e., optical waveguides which guide only light with a specific linear polarization have many potential uses in integrated opto-electronic or all optical devices and circuits. One important application of such waveguides would be in filtering undesired polarization components in the optical circuit, e.g., to prepare the guided mode for interaction with various optical devices which are polarization sensitive. Furthermore, such devices would be useful in conjunction with polarization-rotation devices for performing light intensity modulation.
The novel waveguide structures disclosed herein can be produced by impurity-induced disordering of semiconductor superlattice heterostructures whereby the refractive index distribution in the plane of the superlattice layers can be patterned. This technique has been described by W. D. Laidig et. al. in Applied Physics Letters, 38, 776 (1981) and has been employed in the fabrication of index-guided injection lasers [R. L. Thornton et al. Applied Physics Letters, 48, 7 (1986)] and optical channel waveguides [F. Julien et. al. Applied Physics Letters, 50, 866 (1987)]. However, little has been reported about the waveguiding properties of such disordered lattice waveguides.
I have now discovered that certain specifically designed waveguides, e.g., superlattice structures having specific relationships with respect to the dielectric constant of the waveguide medium as well as the surrounding medium, guide laterally only a single mode of polarized light and can operate as efficient waveguide polarizers.